In semiconductor manufacturing, ion implantation is used to change the material properties of portions of a substrate. Indeed, ion implantation has become a standard technique for altering properties of semiconductor wafers during the production of various semiconductor-based products. Ion implantation may be used to introduce conductivity-altering impurities (e.g., dopant implants), to modify crystal surfaces (e.g., pre-amorphization), to created buried layers (e.g., halo implants), to create gettering sites for contaminants, and to create diffusion barriers (e.g., fluorine and carbon co-implant). Also, ion implantation may be used in non-transistor applications such as for alloying metal contact areas, in flat panel display manufacturing, and in other surface treatment. All of these ion implantation applications may be classified generally as forming a region of material property modification.
In a typical doping process, a desired impurity material is ionized, the resulting ions are accelerated to form an ion beam of a prescribed energy, and the ion beam is directed at a surface of a target substrate, such as a semiconductor-based wafer. Energetic ions in the ion beam penetrate into bulk semiconductor material of the wafer and are embedded into a crystalline lattice of the semiconductor material to form a region of desired conductivity.
An ion implanter system usually includes an ion source for generating ions. Associated with the ion source may be a supply mechanism that supplies an ionizable gas into an ion source chamber or other ionizer. The ionizable gas is obtained either directly from a gaseous feed material (e.g., a canister of compressed gas or safe delivery system (SDS)) or indirectly from a solid feed material that has been vaporized in a vaporizer crucible. In either case, it is desirable that the feed material be of a consistently high quality to ensure repeatable ion generation results.
A number of factors may affect the quality of a feed material. For example, a feed material may become contaminated during storage or transportation. If the feed material has been exposed to atmosphere, moisture or other contaminants may be introduced. Some feed materials may deteriorate over time and cannot be safely used or re-used after a designated period of time. Some feed materials are shipped with co-fillers or additives which can also become contaminated. When a non-gaseous feed material is supplied from a vaporizer, internal surface properties of the vaporizer may also contribute to the deterioration or contamination of the feed material. For instance, the vaporizer crucible may become contaminated after being heated for a period of time and may contribute to molecular break-ups and/or other unwanted processes. More novel types of feed materials (e.g., boranes and carborane) may be even more susceptible to contamination and therefore require an even tighter control.
Currently, however, there lacks a systematic approach to effectively and efficiently control the supply of ion source feed materials in semiconductor manufacturing environment.
In view of the foregoing, it would be desirable to provide a technique for providing ion source feed materials which overcomes the above-described inadequacies and shortcomings.